Silicon carbide has a larger band gap, more excellent in dielectric breakdown property, heat resistance, radiation resistance and the like as compared with silicon. Accordingly, it has been noticed as electronic device materials such as portable and high output semiconductors and the like. Further, due to excellent optical properties, it has been noticed as optical device materials. Among such silicon carbide crystals, silicon carbide single crystals have a merit that they are particularly excellent in uniformity of properties in wafer when applied to devices such as wafers and the like as compared with silicon carbide polycrystals.
Modified Lely method is known as a method of producing the above-mentioned silicon carbide single crystal. In the method, a sublimation raw material is held in a first end portion in a reaction vessel (crucible). A seed crystal of a silicon carbide single crystal is placed in a second end portion (seed crystal placing part) in the reaction vessel. The second end portion is positioned to face substantially the sublimation raw material. A silicon carbide single crystal is grown by subliming the sublimation raw material and then recrystallizing the sublimed raw material on the seed crystal.
When the seed crystal is grown without being completely bonded to the seed crystal placing part in Improved Lely method, macroscopic defects (void defects) penetrate through the seed crystal from the side of the seed crystal placing part where the seed crystal is not completely bonded into the growing crystal, and the quality of the wafer was liable to be impaired. Since the adhesive is gasified at high temperatures, it has been also conjectured that remaining bubbles of the gasified adhesive in the adhesive layer causes deterioration of the quality of the crystal.
Several techniques have been proposed as means for solving the above-mentioned problems (for example, refer to Patent Documents 1 and 2). For example, Patent Document 1 discloses a method of fixing a seed crystal of a silicon carbide single crystal by applying a predetermined pressure to the seed crystal. Patent Document 2 discloses a fixing method in which a weight is placed on a seed crystal of a silicon carbide single crystal for press-bonding the seed crystal onto the seed crystal placing part.
However, it was difficult to uniformly bond the entire surface of the seed crystal by the mechanical press-bonding method since it causes the surface of the seed crystal finely roughened. The press-bonding method using the weight also has difficulty in achieving uniformly press-bonding the entire surface of the seed crystal of a silicon carbide single crystal.
As has been described above, so far it has been expected that a seed crystal fixing device achieving uniformly press-bonding the entire surface of the seed crystal of a silicon carbide single crystal so as to grow the seed crystal while the seed crystal completely bonded with the seed crystal placing part.    Patent Document 1; Japanese Patent Application Publication No. 2001-139394    Patent Document 2: Japanese Patent Application Publication No. 2003-119098